Amazon currently has a pretty popular pair of AUKEY Latitude Wireless Headphones on sale, bringing them down from $25.99, to just $18.97 when you use the promo code AUKEY003 at checkout.
This pair of wireless headphones from AUKEY are pretty lightweight. These are not the collar-style headphones that you see from LG and other companies, but just a pair of earbuds with a cable running between them. These are wireless and do use Bluetooth 4.1 for connecting to your smartphone and such. Additionally, battery life is pretty decent here, coming in with around eight hours of continuous playback. These are also a great pair of headphones to take to the gym, or out on a run, since they are IPX4 rated so they can take some sweat. But overall, these are a really good pair of headphones for around $25, and now that these are under $20, they are even better.
This item is also eligible for Amazon Prime's free shipping. Which includes free two-day shipping, and pretty cheap (usually $3.99) next-day shipping if you need it extra fast. If you are not an Amazon Prime member yet, you can sign up for a free trial of Amazon Prime. You'll get 30 days free (if you're a student, you get 6 months), and then it's $99/year (or $49/year for students). Prime members do get a whole lot more than just free shipping though, so be sure to check out the full benefits.